The present invention relates to an improved conveyor belt fastener and more particularly to a strip or aligned row of a plurality of preformed individual fasteners with an anti-sifting means for conveyor belts.
Hinge belt fasteners are generally secured in a juxtaposed array or alignment at one belt end, intermeshed with similar fasteners at the second belt end and secured in this mated arrangement by a rod or hinge pin. These intermeshed belt fasteners and hinge pin form a belt splice for a continuous belt.
Conveyor belts are frequently provided in predetermined lengths, with belt fasteners securing the two ends of the belt lengths together to form a continuous belt. The belt fasteners are stapled, riveted or otherwise fastened to one of the belt ends and thereafter joined together by this hinge pin or hinge rod.
Goods transported on the assembled conveyor belts often are or contain particulate matter with entrained, small sieve size particles, as well as fine, powdery products, which may be dust laden. For example, when transporting grain small fines may sift through the belt splice. A particular problem is the sifting of coal dust through the splice. The sifted coal dust may build up as a cake. Dust is a problem in coal mines as it maybe a source of an explosion; or when accumulated beneath a conveyor, the trail of the coal dust may serve as a wick or fuse along which fire could travel from one location to another location. Thus, sifting grain dust or coal dust may provide a large volume of airborne particulate matter, which provides a large surface area for rapid oxidation and thus a potentially explosive environment. Consequently, it is desirable to minimize dust flowing through a traveling splice on a conveyor belt.
Stated differently, a typical belt splice has a gap separation and a considerable volume of "dust" or particulate matter may sift through the coupling assembly joining the belt ends in a continuous belt transport system. Although there have been efforts to minimize the sifting of fine particles through the belt to reduce the entrained particulates, these anti-sifting devices have not met with wide spread commercial success.
A problem with anti-sifting devices heretofore developed is that they often interfered with the sliding insertion of a hinge pin making it difficult to insert or remove the hinge pin. People doing the splicing may use a hinge pin of a size that will not slide readily through these anti-sifting devices. Other users want anti-sifting devices that are easily added or removed from the splice; and these prior art devices often are molded or stapled in position and are not readily added or removed in the field, as desired by the users. Additionally, these molded inserts are relatively expensive and a more cost effective anti-sifting device is needed.
Indicative of the earlier efforts at the formation of anti-sifting joints in continuous belt arrangements is U.S. Pat. No. 4,653,156, wherein a conveyor fastener with a plurality of elements couples the belt ends. A preformed molded body of solid rubber with eye lug grooves and fin elements is aligned in the fastener with the respective eye lugs of the connecting strip of plural fastener elements, which solid molded body at least partly encompasses the coupling rod. The fin elements and eye grooves form pockets to receive the mating outer parts of the alternative interlocking conveyor belt fastener strips. Often, the size of the hinge pin is varied to join the belt ends together and for smaller diameter pins there will be spaces into which and through which dust or fines may travel. If a larger size hinge pin is used, the solid rubber may grab and hold the pin making it difficult to slide into position.
U.S. Pat. No. 4,540,389 to Ramsey utilizes a planar spacer and two outer planar belt clamping elements. Each of the belt ends is clamped between a belt clamping element and the planar surface and secured by at least one through-bolt and nut. This provides an extending bar of the planar spacer, clamping elements and retained belt ends, which bar is generally perpendicular to the plane of the belt and extends outwardly from its upper surface. Thus, the belt ends are joined and sifting may be minimized but the belt ends are not provided in the belt longitudinal operating plane of the belt; there is a discontinuity in the belt surface, and there is the potential for an increase in the noise level as the belt traverses the sprockets and rollers.
Belt splicing devices with overlapping plates and/or belt ends are noted in U.S. Pat. Nos. 9,080 (Smith); 1,918,257 (Forsyth); 2,330,434 (Lazzeu); 2,446,311 (Traxler); 3,093,005 (Dean); and, 3,327,359 (Wiese). However, these devices are clamping and securing devices which are stiff and relatively inflexible apparatus. Although these assemblies will in some manner and to some degree prevent the filtering of material through the belt joint, they are not operable with a plurality of individual and intermeshed fasteners joined by a pin or other connection. The illustrated clamps or brackets are relatively inflexible and not applicable to multiple fastener assemblies, particularly thin-armed fasteners with looped ends extending from each belt end.
French Patent No. 2,593,872 to Jean F. Schick illustrates a conveyor belt junction with two sets of U-shaped clasps wrapped around a hinge pin fastened by staples against removal and enclosing shaped filler profiles of a generally compressible material. A V-shaped continuous-profile element of a compressible material is formable to fill voids, and is provided with a preformed semicircular end. The preformed semi-circular ends are aimed and sized to receive a given diameter for a hinge pin. The insertable element conforms to the faces of the extending arms and is a compressible material that is displaced to fill voids between the fingers of the clasps at final assembly. The filler profiles are not removable and will engage and make difficult the insertion of a large diameter hinge pin.
Another anti-sifting device of the prior art is a strip swellable material which has an adhesive for attaching to the cut belt end. In coal mines, the ends of a belt may be coated with coal dust, and the adhesive on the strip often cannot be made to stick to the cut belt end. Also, the strip is small in size until water is applied to the strip. The water causes the strip to swell and to increase in size. There are often wet, dripping areas or other sources of water in a mine and the strip may be wetted in an accidental or incidental manner prior to being properly positioned adjacent the belt fasteners and the untimely subsequent swelling of the strip makes it difficult or impossible to use the strip. Such strips of swellable material have serious shortcomings.